(50 days)
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Wako Total Bilirubin V is based on a chemical oxidation method, utilizing vanadate as an oxidizing agent, shows good correlation with conventional methods, practically no interference by coexistent serum substances, and is convenient ready-to-use liquid type reagent. When a sample is mixed with the reagent containing the detergent and the vanadate, at around pH 3, direct bilirubin in the sample is oxidized to biliverdin. This causes the absorbance of yellow, specific to bilirubin, to decrease. Therefore, the direct bilirubin concentration in the sample can be obtained by measuring the absorbance before and after the vanadate oxidation.
Here's an analysis of the provided text regarding the Wako Direct Bilirubin V assay, structured to address your specific points.
Wako Direct Bilirubin V Assay: Acceptance Criteria and Study Details
The provided document describes the Wako Direct Bilirubin V assay and its demonstration of substantial equivalence to a predicate device. This is a clinical laboratory device used for measuring serum bilirubin, not an AI/ML powered medical device. Therefore, many of the requested points related to AI/ML specific studies (e.g., MRMC studies, training set details, expert ground truth adjudication) are not applicable.
1. Table of Acceptance Criteria and Reported Device Performance
Given the nature of this submission (510(k) for a laboratory diagnostic), the acceptance criteria are primarily focused on demonstrating analytical performance and substantial equivalence to a predicate device, rather than diagnostic accuracy against a clinical gold standard (which would be more common for imaging or AI devices).
| Acceptance Criteria Category | Specific Criteria/Goal | Reported Device Performance (Wako Direct Bilirubin V) |
|---|---|---|
| Substantial Equivalence | Comparison to predicate device (Wako Direct Bilirubin assay, K912024/A) | Achieved; Correlation coefficient of 0.997 and regression equation y=1.003x + 0.09. |
| Correlation | Strong positive correlation with predicate device | 0.997 |
| Regression Slope | Close to 1 (indicating proportional agreement) | 1.003 |
| Regression Intercept | Close to 0 (indicating no significant constant bias) | 0.09 |
| Precision | Acceptable values on a day-to-day basis | "Precision studies indicate acceptable values can be obtained on a day to day basis." (No specific quantitative values provided in summary) |
| Minimum Detectable Level | Quantifiable limit for bilirubin detection | 0.03 mg/dL |
| Linearity | Accurate measurement across a relevant range | Linear to 20 mg/dL |
| Interference | Minimal interference from coexistent serum substances | "practically no interference by coexistent serum substances" |
| Reagent Stability | Improved stability compared to older methods | Implied improvement over methods with "unsatisfactory stability of reagents after preparation." |
| Convenience | Ready-to-use liquid type reagent | "convenient ready-to-use liquid type reagent" |
2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
- Sample Size for Test Set: The document states that "serum samples" were used for comparison studies, but does not specify the number of samples used in the correlation and regression analysis.
- Data Provenance: Not specified. It's common for such studies to use banked clinical samples, but the source (e.g., country, specific hospitals) is not mentioned.
- Retrospective/Prospective: Not specified, but generally, analytical validation studies for laboratory diagnostics often use a combination of pre-collected (retrospective) samples and sometimes prospectively collected samples to ensure a wide range of analyte concentrations and potential interferents.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
Not applicable. As a chemical diagnostic assay, the "ground truth" for the test set is established by the predicate device's measurement of bilirubin concentration, not by expert interpretation. Experts are not involved in adjudicating bilirubin values from a chemical assay.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
Not applicable. This is a chemical assay, and adjudication methods are typically used for subjective interpretations by human experts (e.g., reading medical images). The "ground truth" is the quantitative measurement provided by the reference method (predicate device).
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
Not applicable. This is not an AI/ML powered device, nor does it involve human readers interpreting results. It's a laboratory diagnostic assay.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
Yes, in essence, a "standalone" performance was evaluated. The Wako Direct Bilirubin V assay's performance was compared directly to the predicate device's performance, without human "interpretation" influencing the analytical results. The reported correlation and linearity studies evaluate the device's inherent measurement capability.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
The "ground truth" for this comparative study was the measurement result obtained from the predicate device (Wako Direct Bilirubin assay, 510(k)#K912024/A) on the same serum samples. This is a common approach for demonstrating substantial equivalence for in vitro diagnostics where a clinically accepted reference or predicate method exists.
8. The sample size for the training set
Not applicable. This is a chemical assay, not an AI/ML model, so there is no "training set" in the machine learning sense. The assay works based on established chemical reactions.
9. How the ground truth for the training set was established
Not applicable. As there is no training set for an AI/ML model, this point is not relevant.
§ 862.1110 Bilirubin (total or direct) test system.
(a)
Identification. A bilirubin (total or direct) test system is a device intended to measure the levels of bilirubin (total or direct) in plasma or serum. Measurements of the levels of bilirubin, an organic compound formed during the normal and abnormal distruction of red blood cells, if used in the diagnosis and treatment of liver, hemolytic hematological, and metabolic disorders, including hepatitis and gall bladder block.(b)
Classification. Class II.